30 CARTILAGE. BONE. TEETH. 



its surface, derived from ihe plasmatic cells of the 

 perichondrium as already described. It lias not been 

 demonstrated that cartilage is ever reproduced when 

 destroyed by disease or injury ; it is replaced by 

 transformed plasmatic cells, as far as the process can 

 be traced.* 



To study the structure of cartilage very thin slices 

 should be cut from it by means of a razor. 



SECT. II. BONE. To study advantageously the mi- 

 nute anatomy of bone, sections as thin and delicate 

 as possible, should be made with a saw in every direc- 

 tion through its substance, and the laminae thus pro- 

 cured should be rubbed down with moistened pumice 

 stone, and afterwards polished upon a fine whetstone. 

 It is well also to examine, in connexion with these, 

 the delicate and transparent scales which form the 

 walls of the cancelli of the spongy portion of the bony 

 tissue ; they can be readily detached, and when placed 

 between two slips of glass, and moistened with a drop 

 of water, are ready for use. 



structure of In a transparent lamina of bone thus prepared, 



when placed under the microscope, there are always 

 two elements to be recognised, and these alone con- 

 stitute true osseous tissue, viz. bone cells, and the 



* There are many points connected with the histology of cartilage, and 

 especially of articular cartilage, still unsettled, and in consequence of the 

 important bearing of this knowledge upon the principles of surgery, as 

 applied to diseases of joints, I cannot refrain from calling attention to the 

 admirable papers of Mr. R. Harwell, F.R.C.S.E., Ast. Surgeon Charing 

 Cross Hosp'l, Lond., in the No. for October, 1859, of the Medico- Chirur- 

 gical Review, and in the No. for February, 1860, of the Edinburgh Me- 

 dical Journal. They are complementary to the researches of Ecker, 

 Goodsir, and Redfern, and comprise the fullest knowledge of the subject 

 yet acquired by science. (Ed?) 



